Distribution of [S-35]dATP alpha S binding sites in the adult rat neuraxis

Highly abundant, saturable and specific binding sites for [S-35]2prime-deoxyadenosine 5prime-O-(1-thio) triphosphate ([S-35]dATPalphaS, K-d: 9plusminus 2nM; B-max: 39 plusminus: 39 plusminus 8 pmol/mg protein) are present in adult rat brain membranes and have characteristics consistent with those expected for a PSY1 receptor. The anatomical distribution of these binding sites in the brain and spinal cord was examined using in vitro autoradiography. The [S-35]dATPalphaS binding sites showed a widespread distribution throughout the brain and spinal cord. They could be displaced by a large excess (100 muM) of 2-methylthioATP (2MeS-ATP) but not by uridine-5prime-triphosphate (UTP) or alpha,beta-methyleneATP (alpha,beta-meATP). Within the cortical regions labelling was of equal medium density. However, discrete structures and nuclei within the olfactory bulb, subcortical telencephalon, hippocampal complex, thalamic regions and mesencephalon displayed a variety of densities. Within the spinal cord, gray matter was labelled at a greater density than the funiculi. The present study clarifies the anatomical distribution of P2Y(1) and closely related receptors within the central nervous system of rat and extends the evidence that those receptors are abundant and widely distributed within the neuraxis. (C) 1997 Elsevier Science Ltd.